Process for the surface treatment of light alloy components, more particularly for the abrasive blast treatment of light alloy castings



United States Patent 9 PROCESS FOR THE SURFACE TREATMENT OF LIGHT ALLOY COMPONENTS, MORE PARTICU- LARLY FUR THE ABRAIVE BLAST TREAT- MENT OF LIGHT ALLOY CASTINGS Fritz Nikolaus Bischoii, Schaiihausen, and Hans Paul Hiiberlin, Neuhausen am Rheinfali, Switzerland, assignors to Georg Fischer Aktiengesellschaft, Schnithausen, Switzerland, a Swiss company No Drawing. Application July 23, 1952, Serial No. 300,528

Claims priority, application Switzerland July 24, 1951 3 Claims. (Cl. 51-282) This invention relates to the surface treatment of. light metal castings and like parts.

In order to impart a uniform surface finish to light alloy components and for example in the case of light Weight metal alloy castings, to remove from the castings the scars left by flash metal, sprues or risers, it is known practice to subject such components or castings to an abrasive blasting process. Quartz sand, with which the parts are blasted with the aid of compressed air or centrifugal impellers has hitherto been the medium in most widespread use for this purpose.

A serious drawback of this method resides in the fact that working with such sandblasting apparatus entails grave damage, in the form of silicosis, to the health of the operating personnel. Moreover, owing to their impact on the metal components being treated, the grains of quartz sand are prematurely broken down and their effect thereby materially impaired.

In order to avoid this drawback and other difficulties which arise in the use of sandblasting equipment, it has been proposed to use primarily steel or iron shot or iron grit as the abrasive blasting medium. When used for blast-cleaning components made of light weight metals or alloys thereof, this method entails the drawback that a thin film of iron dust, which can only be removed with great difficulty and inevitably causes rust to form on the components as soon as they are exposed to the action of atmospheric moisture, is formed on the surfaces of the components.

In order to enable the surfaces of light weight metal or alloy castings and like shapes to be treated without detriment to the components or to the health of the person or persons performing the treatment, it is proposed according to the invention that light Weight metal or allay with an atomic weight ranging from 24 to 27, such as aluminum shot or grit of appropriate grain size and grain hardness be used as the medium for the surface treatment of the light alloy components.

By correct selection of the alloy of the light metal or alloy shot it is possible to achieve, if desired, a material of the greatest possible hardness. It is also possible to 2,773,339 iatented Dec. 11, 1956 particulate large-grained shot, lathe swarf, etc., in crushing equipment so as to produce angular light alloy grit of smaller size.

Another possibility is to use wire made of alloys of light weight metal, such as anticorrodal wire, manufactured by a drawing process, and cut into lengths equivalent to once or twice the thickness of the wire. In the experiments conducted abradant particles of light weight alloy comprising 16.5% copper, 0.4% manganese, 1.4% iron, 0.3% silicon and the balance aluminum consequently in an amount of not less than about of the total weight of the said alloy proved to be particularly well suited for the purpose of the invention.

The process can be performed either with the aid of equipment in which the abrasive medium is accelerated by a stream of air or with the aid of equipment in which centrifugal impellers are used. Extensive practical tests have shown conclusively that the invention constitutes a substantial advance in the surface treatment of shapes, components or castings made of light weight metal alloys.

Various changes and modifications may be made without departing from the spirit and scope of the present invention and it is intended that such obvious changes and modifications be embraced by the annexed claims.

Having thus described the invention, What is claimed as new and desired to be secured by Letters Patent, is:

What we claim is:

1. In the process of blast-treating shapes, castings and the like; the step of directing against the surface of the casting made of light weight metal with an atomic weight ranging from 24 to 27 shots, grits, slugs and like particles obtained from an alloy of light weight metal consisting predominantly of aluminum in an amount not less than approximately 80% of the total weight of said alloy.

2. For use in the blast-treatment of castings and like shapes made of light weight metal with an atomic weight ranging from 24 to 27; alloy shots and like particles consisting essentially of about 16.5% by Weight of copper, about 0.4% by weight of manganese, about 1.4% by weight of iron, about 0.3% by weight of silicon, the balance being aluminum.

3. For use in the blast-treatment of castings and like shapes made of light weight metal with an atomic weight ranging from 24 to 27; pieces of wire cut into lengths substantially corresponding to approximately once to twice the thickness of said Wire, said Wire being made of light weight metal alloy consisting essentially of about 16.5% by weight of copper, about 0.4% by weight of manganese, about 1.4% by weight of iron, about 0.3% by weight of silicon, the balance being aluminum.

References Cited in the file of this patent UNITED STATES PATENTS 983,028 Davidson Jan. 31, 1911 1,682,246 Read Aug. 28, 1928 2,149,253 Cooper Mar. 7, 1939 2,600,358 Bolton et a1. June 10, 1952 

1. IN THE PROCESS OF BLAST-TREATING SHAPES, CASTINGS AND THE LIKE; THE STEP OF DIRECTING AGAINST THE SURFACE OF THE CASTING MADE OF LIGHT WEIGHT METAL WITH AN ATOMIC WEIGHT RANGING FROM 24 TO 27 SHOTS, GRITS, SLUGS AND LIKE PARTICLES OBTAINED FROM AN ALLOY OF LIGHT WEIGHT METAL CONSISTING PREDOMINATLY OF ALUMINUM IN AN AMOUNT NOT LESS THAN APPROXIMATELY 80% OF THE TOTAL WEIGHT OF SAID ALLOY. 